Adobe changed the PDF specification several times and continues to develop new specifications with new versions of Adobe Acrobat. There have been nine versions of PDF with corresponding Acrobat releases:

The ISO standard ISO 32000-1:2008 is equivalent to Adobe's PDF 1.7. Adobe declared that it is not producing a PDF 1.8 Reference.

PDF 2.0

A new version of PDF standard is under development under the name ISO/NP 32000-2 - Document management—Portable document format—Part 2: PDF 2.0 (as of January 2011). Adobe has submitted the Adobe Extension Level 5 and Adobe Extension Level 3 specifications to ISO for inclusion into the next version of the ISO 32000 specification. Adobe declared they have all been accepted for part 2 of ISO 32000

I was looking for a PDF editor to fix some irritating typos and inaccuracies in PDFs of boardgame rules before printing them (many specialty boardgame publishers provide additional copies of their rules in freely-downloadable PDFs). I had tried PDFEDIT (GPL'd software) under Linux, but it was quite buggy and the user interface was horrible.

So I downloaded demo versions of a couple of programs that work under WinXP: Nitro PDF Professional 6 (demo is full version, limited to 14 days), and Foxit PDF Editor 2.2 (demo version puts an "evaluation mark" at the corner of each page). The non-crippled version of each has a purchase price of $99.

Using the PDF I currently wanted to fix, I first tried Nitro. I could not edit text successfully (perhaps because the font was an embedded subset, but that's pure speculation based on general ignorance of PDF technology), and gave up after about an hour fiddling with different things. I then tried Foxit on the same PDF, and it worked like a charm. I was able to change text and add text immediately. Later I added a transparent graphic, also very easily. It was easy to learn to use, and the user interface was intuitive. The program Help was very good, and the 140-page manual seems to cover things pretty well.

For reference, the PDF I used was marked as PDF 1.6, produced by QuarkXPress 7.5.

My impression is that the Foxit Editor is oriented towards modification of existing PDFs rather than creation of new ones (though it can do that). Since that's what I want it for, it looks perfect for me. The only issue (for the amount of use I will make of it) is the price, although it's only one-third of the cost of Adobe Acrobat.

Based on an extremely limited sample of PDFs , I give a to Foxit PDF Editor 2.2, and I expect I will end up forking out that $99 (after I've tested compatibility with a few more PDFs).

It has been less than 3 months, but already the $99 Foxit version 2.2 is gone and has been replaced by a $129 Foxit PhantomPDF Standard or a $199 PhantomPDF Business. For editing, they recommend the Business model.

[email protected], do you print to pdf from your Internet browser and much too often find that Nitro has made the proper title of the file disappear and replaced it with Untitled.pdf?Mine does this quite often, and it is disappointing. I have not been able to spot any pattern in when it does or doesn't.

Fully edit PDFs from anywhere, with more flexibility than any other desktop publishing software – ideal for updating and refreshing existing documents or correcting errors in PDFs before they are distributed or printed. Full PDF editing power lets you move, resize, recolour, replace anything in the design, add new text and images, include bookmarks and notes, merge multiple PDFs, manage pages, and add security. It’s like editing a normal PagePlus file – there is nothing you can’t do!

This is one of the longer running threads, so I'll bring up the topic of Adobe again. Much earlier posts remarked on interface problems - for Acrobat 10 Adobe put about half of the features into a sliding command bar on the right side. It looks simple enough to me. Meanwhile, a big new feature in Adobe Pro is it can mostly compare two PDFs and annotate a report with the differences. So sometimes if the "flagship program" in a field can keep innovating, it knocks out a lot of the alternatives. So for editing, it's Adobe Pro for me.

-I already have Nitro 7 Pro, but have reached the level where I no longer am satisfied. It is a very fine editor and converter, but the virtual printer (print homepage article to pdf) is not impressive. Of course the sinner could be Firefox, I don't know for sure.